A modified TC-MAC protocol for multi-hop cluster communications in VANETs

The transmission of safety/update message aims to inform the nearby vehicles about the senders current status and/or a detected dangerous situation. This type of transmission is designed to help in accident and danger avoidance. Moreover, it requires high message generated rate and high reliability. On the other hand, the transmission of non-safety message aims to increase the comfort on vehicles by supporting several non-safety services, from notifications of traffic conditions to file sharing. Unfortunately, the transmission of non-safety message has less priority than safety messages, which may cause shutting down the comfort services. The goal of this paper is to design a MAC protocol in order to provide the ability of the transmission of non-safety message with little impact on the reliability of transmitting safety message even if the traffic and communication densities are high in a multi-hop cluster. Our protocol is based on modifying TC-MAC which uses TDMA technique for slot reservation based on clustering of vehicles.